We began our journey through the Solar System
exploring the planets. We discovered that they follow certain
rules. These rules say that the inner planets are small and
dense while the outer planets are large and gaseous. We
discovered that planets in the same part of the Solar System are
alike, such as Earth and Venus, or Uranus and Neptune.

Studying the planets does not, however, conclude our
journey. There are other things, other very exciting things
still to explore in the Solar System. In this astronomy packet
we are going to discuss the Asteroid Belt (where asteroids come from),
and the Kuiper Belt and Oort cloud (where comets come from). We
will then learn about the moons of our Solar System.

The Asteroid Belt:

If you traveled towards the planet Jupiter, along
your way you would have to fly though an area called the Asteroid
Belt. The Asteroid Belt sits between the planets Mars and
Jupiter. It is a region of space where millions of rocks can be
found circling the Sun. Some of these rocks are very big, like
Ceres which is over 500 miles long. Others are as small as a
baseball. But most are medium size, about the size of your house.

Are asteroids only found in the Asteroid Belt?

This is an important question to think about.
As long as asteroids remain in the Asteroid Belt they cannot harm
the Earth. It is the ones which stray from the belt which worry
us. Unfortunately, not all asteroids are found in the asteroid
belt. It is believed that at least 5000 asteroids have an orbit
which leaves the asteroid belt, and brings them in towards the
Earth. Don't worry, the really big ones only hit the Earth
about every 100 million years.